Analysis

  • max time kernel
    97s
  • max time network
    137s
  • platform
    windows10_x64
  • resource
    win10v20210408
  • submitted
    16/09/2021, 12:42

General

  • Target
    Gatdhaozmwzqbfqrwgmuappjkqvltpfcxj.exe
  • Size 713KB
  • Sample210916-pxb5qagcfl
  • SHA256 e65c6e141516a7d76fe7c1e3bcc5433758fa627dfd6c18f65504efcfa62d4855
  • MD5 SHA1 SHA512

Malware Config

Extracted

Family
  • oski

C2
  • 103.141.138.110/p1/

Signatures

  • Oski

    Oski is an infostealer targeting browser data, crypto wallets.

  • suricata: ET MALWARE Suspicious Zipped Filename in Outbound POST Request (Passwords.txt)

    suricata: ET MALWARE Suspicious Zipped Filename in Outbound POST Request (Passwords.txt)

  • suricata: ET MALWARE Vidar/Arkei/Megumin/Oski Stealer Data Exfil

    suricata: ET MALWARE Vidar/Arkei/Megumin/Oski Stealer Data Exfil

  • Downloads MZ/PE file
  • Loads dropped DLL 3 IoCs
  • Reads user/profile data of web browsers 2 TTPs

    Infostealers often target stored browser data, which can include saved credentials etc.

  • Accesses cryptocurrency files/wallets, possible credential harvesting 2 TTPs
  • Adds Run key to start application 2 TTPs 1 IoCs
  • Checks installed software on the system 1 TTPs

    Looks up Uninstall key entries in the registry to enumerate software on the system.

  • Suspicious use of SetThreadContext 1 IoCs
  • Enumerates physical storage devices 1 TTPs

    Attempts to interact with connected storage/optical drive(s). Likely ransomware behaviour.

  • Checks processor information in registry 2 TTPs 1 IoCs

    Processor information is often read in order to detect sandboxing environments.

  • Kills process with taskkill 1 IoCs
  • Modifies registry key 1 TTPs 3 IoCs
  • Suspicious use of AdjustPrivilegeToken 1 IoCs
  • Suspicious use of WriteProcessMemory 32 IoCs

Processes

  • C:\Users\Admin\AppData\Local\Temp\Gatdhaozmwzqbfqrwgmuappjkqvltpfcxj.exe
    "C:\Users\Admin\AppData\Local\Temp\Gatdhaozmwzqbfqrwgmuappjkqvltpfcxj.exe"
    1⤵
    • Adds Run key to start application
    • Suspicious use of SetThreadContext
    • Suspicious use of WriteProcessMemory
    PID:656
    • C:\Users\Admin\AppData\Local\Temp\Gatdhaozmwzqbfqrwgmuappjkqvltpfcxj.exe
      C:\Users\Admin\AppData\Local\Temp\Gatdhaozmwzqbfqrwgmuappjkqvltpfcxj.exe
      2⤵
      • Loads dropped DLL
      • Checks processor information in registry
      • Suspicious use of WriteProcessMemory
      PID:1104
      • C:\Windows\SysWOW64\cmd.exe
        "C:\Windows\System32\cmd.exe" /c taskkill /pid 1104 & erase C:\Users\Admin\AppData\Local\Temp\Gatdhaozmwzqbfqrwgmuappjkqvltpfcxj.exe & RD /S /Q C:\\ProgramData\\926492109393506\\* & exit
        3⤵
        • Suspicious use of WriteProcessMemory
        PID:2704
        • C:\Windows\SysWOW64\taskkill.exe
          taskkill /pid 1104
          4⤵
          • Kills process with taskkill
          • Suspicious use of AdjustPrivilegeToken
          PID:3752
    • C:\Windows\SysWOW64\cmd.exe
      C:\Windows\system32\cmd.exe /c ""C:\Users\Public\Trast.bat" "
      2⤵
      • Suspicious use of WriteProcessMemory
      PID:1280
      • C:\Windows\SysWOW64\cmd.exe
        C:\Windows\system32\cmd.exe /K C:\Users\Public\UKO.bat
        3⤵
        • Suspicious use of WriteProcessMemory
        PID:1648
        • C:\Windows\SysWOW64\reg.exe
          reg delete hkcu\Environment /v windir /f
          4⤵
          • Modifies registry key
          PID:2032
        • C:\Windows\SysWOW64\reg.exe
          reg add hkcu\Environment /v windir /d "cmd /c start /min C:\Users\Public\KDECO.bat reg delete hkcu\Environment /v windir /f && REM "
          4⤵
          • Modifies registry key
          PID:2148
        • C:\Windows\SysWOW64\schtasks.exe
          schtasks /Run /TN \Microsoft\Windows\DiskCleanup\SilentCleanup /I
          4⤵
            PID:2256
      • C:\Windows\SysWOW64\cmd.exe
        C:\Windows\system32\cmd.exe /c ""C:\Users\Public\nest.bat" "
        2⤵
        • Suspicious use of WriteProcessMemory
        PID:3040
        • C:\Windows\SysWOW64\reg.exe
          reg delete hkcu\Environment /v windir /f
          3⤵
          • Modifies registry key
          PID:4068

    Network

          MITRE ATT&CK Enterprise v6

          Replay Monitor

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          Downloads

          memory/656-114-0x0000000000560000-0x00000000006AA000-memory.dmp

          memory/1104-120-0x0000000000400000-0x0000000000438000-memory.dmp

          memory/1104-115-0x0000000000400000-0x0000000000438000-memory.dmp